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The working load limit of all components used to block cargo from forward movement must be 50% (or more) of the weight of the article being blocked.
The most important securement task is to prevent an article from moving forward, and the best way to prevent forward movement is to immobilize the cargo.
This can be done by placing it against a headboard, bulkhead, stakes or other vehicle structure, or against other cargo that is immobilized in that manner. Blocking and bracing can be placed between the article and vehicle structure, other cargo, or a void-filler.
A “void-filler” is material used to fill a space between articles of cargo and the structure of the vehicle, that has sufficient strength to prevent movement of the articles of cargo (for example, 4 ft. x 4 ft. timbers placed between two adjacent articles of cargo to fill the void).
A direct tiedown can also be used to secure cargo against forward movement.
The working load limit of a tiedown is the working load limit of its weakest part, including anchor points (that is, a tiedown is only as strong as its weakest link). In the case of synthetic webbing, the working load limit is the working load limit of the tiedown assembly or the anchor point, whichever is the least.
Some manufacturers mark their manufactured tiedown assemblies, or components, with a numeric Working Load Limit value. In the absence of other information, this value should be used as the working load limit of the component or assembly.
Other manufacturers mark components using a code or symbol that is defined in a recognized standard. For example, a piece of grade 7 chain may be marked with a 7 or 70, in accordance with the standard of the National Association of Chain Manufacturers. The standard then gives the Working Load Limit for that piece of chain, depending on its size.
Securement components and assemblies which are not marked are considered to have working load limits as specified in the Working Load Limit Table
Carriers should try to purchase and use components that are rated and marked by their manufacturer. That way, the carrier, driver, shipper and inspector can all verify that the proper equipment is being used for the job.
Articles of cargo that are placed beside each other and secured by side-to-side, indirect tiedowns must be either:
Some tiedowns lose their initial tension very quickly in normal driving if there are gaps between articles. Articles must be placed in contact with each other to ensure that there are no gaps, or must be secured by some means to prevent them from moving towards each other in transit.
This requirement applies to all layers and stacks of articles that are loaded across a vehicle.
Where two or more long articles (like metal ingots or bundles of reinforcing bars) are loaded lengthwise on a vehicle, if the space between articles cannot be filled with other cargo or blocking, transverse tiedowns can be wrapped around each article to immobilize it against side-to-side movement.
A tapered piece of material, thick at one end and thin at the other, used to help keep cargo from moving.
A structure, device, or another substantial article placed against an article to prevent it from tipping that may also prevent it from shifting.
A device placed between the deck of a vehicle and car or between articles of cargo, intended to provide greater friction than exists naturally between these surfaces.
A rail along the side of a vehicle that protects the side of the vehicle from impacts.
It is accepted that friction mats provide a resistance to horizontal movement equal to:
What is aggregate working load limit?
The summation of the working load limits or restraining capacity of all devices used to secure an article on a vehicle.
What is the minimum WLL used to block forward movement of cargo weighing 36,500 lbs?
The working load limit of all components used to block cargo from forward movement must be 50% (or more) of the weight of the article being blocked.
A friction mat is used to:
A device placed between the deck of a vehicle and car or between articles of cargo, intended to provide greater friction than exists naturally between these surfaces.
What is a rub rail?
A rail along the side of a vehicle that protects the side of the vehicle from impacts.
Blocking is used to:
A structure, device, or another substantial article placed against or around an article to prevent horizontal movement of the article.
In cargo securement, bracing is:
A structure, device, or another substantial article placed against an article to prevent it from tipping that may also prevent it from shifting.
A vertical barrier across the front of the deck of a vehicle to prevent forward movement of cargo is a:
A vertical barrier across the front of the deck of a vehicle to prevent forward movement of cargo.
By definition, what is a wedge?
A tapered piece of material, thick at one end and thin at the other, used to help keep cargo from moving.
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